Implementing package foreign symbol concept.

* eval.c (eval_init): Register new intrinsics:
package-local-symbols, package-foreign-symbols, use-sym,
unuse-sym, use-package, unuse-package, unintern.

* gc.c (mark_obj): Mark new hidhash member of
struct package.

* lib.c (make_package): Initialize new hidhash
member of struct package.
(lookup_package): New static function.
(find_package): Allow string or symbol argument.
(get_package): New static function.
(delete_package, package_symbols): Use get_package for
flexible package argument; delete_package removes
symbols from other packages via unuse_package.
(package_local_symbols, package_foreign_symbols): New
functions.
(use_sym, unuse_sym): New functions.
(resolve_package_designators): New static function.
(use_package, unuse_package): New functions.
(symbol_present): New static function.
(intern): Revised with get_package for flexible
package argument.
(unintern): New function.
(rehome_sym): Use get_package. Semantics revised.
(obj_print_impl): Use symbol_present function to
determine whether object is visible in *package* and
can be printed without a prefix, rather than naive
home package test.

* lib.h (struct package): New member, hidhash.
(package_local_symbols, package_foreign_symbols, use_sym,
unuse_sym, use_package, unuse_package, unintern): Declared.

* txr.1: Documentation updated. Extended section introducing
the design of packages, and argument conventions. New
functions described. Existing function descriptions revised,
particularly rehome-sym.  Missing description of
delete-package added.

1 files changed, 8 insertions, 0 deletions

diff --git a/lib.h b/lib.h
index 9ebfe524..c55bd23c 100644
--- a/lib.h
+++ b/lib.h
@@ -132,6 +132,7 @@ struct package {
   obj_common;
   val name;
   val symhash;
+  val hidhash;
 };
 
 typedef struct args *varg;
@@ -783,7 +784,14 @@ val delete_package(val package);
 val package_alist(void);
 val package_name(val package);
 val package_symbols(val package);
+val package_local_symbols(val package);
+val package_foreign_symbols(val package);
+val use_sym(val use_list, val package);
+val unuse_sym(val symbol, val package);
+val use_package(val use_list, val package);
+val unuse_package(val unuse_list, val package);
 val intern(val str, val package);
+val unintern(val sym, val package);
 val rehome_sym(val sym, val package);
 val symbolp(val sym);
 val symbol_name(val sym);